As a longtime visitor of the old Cosi, and a previous volunteer at the new Cosi, I have to say that while the old Cosi will always hold a special place in my heart, the new Cosi has improved dramatically in the 10 years it's been open. I started volunteering in June of 2000 and the last time I volunteered was December of 2004. Just in my few years volunteering at Cosi, the changes and improvements that were made helped dramatically. Yes, the walls are white. But the carpet is all sorts of colors!:) Don't get me wrong, there are parts of the old Cosi that I miss, like the coal mine. And there are parts of the new Cosi that I miss, like Adventure and the old location of the Space exhibit. But that doesn't mean that I'm going to give up on Cosi! What horrifies me are all of the people who went to Cosi in the new building once 8 or more years ago who hated it instantly and gave up hope. If you haven't been to Cosi in the last year, you don't have a right to complain about how awful it is. I visit Cosi now about once or twice a year, and everytime I go back, there's something new and different. If you take a harder look, I bet that many of the things from the old Cosi that you missed are in the new building. Rat basketball is still around. The pendulum is back in the atrium like it was at 280. Give it a chance!
I can't really speak about the ticket prices because I have a lifetime membership (thanks to my aunt, who was one of the original volunteers at the old Cosi) but I will say this: if you're the type of person/family who travels, a Cosi membership is valid at numerous other science museums across the country. I've used it at so many other places for either free or discounted admission. I wouldn't trade my little green membership card for anything in the world!
Think of Cosi like a car. Picture your very first car. It was probably old and worn down, but you loved it because of the memories you have involving it. Maybe it drove you to high school or took you to college. It was your foundation - what got you started. Then one day, it wasn't meeting your needs. Maybe you got married and started a family and a two-seater just wasn't cutting it anymore! So you got a new car. It's shiny and clean and... sterile! It may take some getting used to, but after awhile it doesn't feel like a 'new car' anymore. It feels like your car.:)